PC Causing Noise On Display and in Audio

Jerry W2TXB

When the 6700 is connected to my desktop PC; I am noticing audible and visible (on the display at somewhat regular intervals) noise on the 20-15 meter bands. I disabled the WiFi and the problem remained unchanged. The only way I can totally remedy the problem is to use the old ThinkPad, and then there is absolutely no noise. My preference is to use the desktop PC rather than the old TP. I am guessing there is something in the PC causing the problem. Any ideas where I should look next?

The PC is a home built unit (Antec metal tower case w/ Corsair 400W PS), Intel 2.5 gHz Core2 Quad, 4GB RAM, and Win-7 SP1. 

Here is the display:




Thanks in advance for the assistance.

Andrew O'Brien

Have you tried the desktop with a different monitor or with the usual monitor and a different display setting ?

George KF2T

Andy's advice is sound - monitors can cause a lot of grief. His recommendation will show very quickly if your monitor is to blame. You could also remote desktop in and turn your monitor off to see what that does.

Other things to try:

Line filter on the PC mains (I like Tripplite's ISOBLOX)
Shielded power cables
Ferrites on everything coming into or going out of the PC and monitors
Shielded monitor cables (DVI seems to work best)
Single point shack ground
Build a shielded enclosure for the monitor power supplies, if they're external, with ferrites on the ins and outs. Ground the enclosure.
Change the PC power supply to a better EMI blocking one
Ensure that all metal to metal cabinet, etc., connections are really metal-to-metal, not paint-to-paint.
Move your PC away from the rig, and especially away from DC and antenna leads

Good luck!

Jerry W2TXB

Duh (to me! Been a long week. ) Thanks for the tip. I shut off the monitor and the noise went away. Now I need to swap it with a different monitor to see if that helps to permanently resolve the problem.

Thanks again!

Jerry W2TXB

Going to swap in another monitor now. One other thing... adjusting the resolution only moves the noise to different frequencies. Back in a few minutes with the results.

G4YDO

what is PC power supply to a better EMI blocking one? it's ok i've just changed my computer and i'm getting noise exspecially on 40m. my new case has a glass side, you think i should change the case?

paul.

Jim KJ7S

The three main things I have run into so far are, Monitors, video cards, and power supplies (which can range from the one on the "local" computer to others in the network close by), to the little wall warts. I have a "GBOX" which is a streaming box that is Droid based, and it makes a real bad noise on the lower bands which forces me to shut it clear down whenever I am on the radio. If you have a LOT of chokes you can clip on to lines, you may be able to reduce, or eliminate most of the noise from the offending culprits.

Jim  KJ7S..

Jerry W2TXB

OK, here's the deal. I tried the ferrite chokes, no joy. Swapped the LED LG monitor (has an 18-Volt wall wart) out for my wife's Asus LCD monitor (120 VAC direct to the back of the monitor - must have a cleaner internal supply), and no more noise on my radio. She gets a slightly larger LED monitor and I get a clean receive. 

Such a deal!

Thanks again to all.

George KF2T

If you're not seeing noise problems, then no need to change. But if you are, yes, then I'd hit the case first. As for the power supply, when I was running a PC, I got some improvement from an Antec VP-450. http://www.abrohamnealsoftware.com/products.php is also a great source, and is often in this community.

Alan C

I have a newer Acer LED monitor that has IPS (In Plane Switching) which is suppose to be somehwat better at various viewing angles. Well, it is VERY noisy! Turning it off - noise goes away! My other Acer LED monitor is not IPS, and has no offending noise.

My 02...